1. Field of the Invention
The invention relates generally to side-release buckles of the type having a female receptacle member and a mating male latch member which are releasably lockable together. More particularly, the invention relates to such a side-release buckle wherein the female receptacle member includes a tooth which is adapted to engage with a centrally aligned groove and latch in a leg of the male latch member, whereby the latch and tooth provide a resistance force in opposition to and in central alignment with a loading force acting to separate the male latch member from the female receptacle member.
2. Description of Related Art
Assorted two-piece buckles are known in the art. These buckles typically include a female receptacle or socket member which is engageable with a male latch or plug member. One or both of the members adjustably or fixedly holds a strap or belt around crossbars or the like. One particularly common form of a two-piece buckle is one in which the plug member includes a pair of legs which, when inserted into the socket member, flex inwardly and slide past opposing stop members (e.g., latches) in the socket until they snap fit into respective side openings in the socket. The stop members are typically inwardly projecting surfaces of the socket member around the periphery of the opening which engage with shoulders defined on the outside edges of the legs of the male member. The two buckle pieces are unlocked and disengaged by squeezing the legs of the male member through the openings in the female member between the thumb and forefinger, thereby freeing the shoulders defined in the legs from the respective stop members in the female member and allowing the two buckle pieces to become separated.
An example of such a buckle is disclosed in U.S. Pat. No. 4,150,464, and a basic configuration of this type of buckle is illustrated in FIGS. 3 and 4. It can be seen that the female member defines apertures in opposing side walls thereof for engagement with shoulders of the latch arms belonging to the male member. The shoulders are positioned on the outside side surfaces of the latch arms and engage the stop members which project inwardly from the side walls of the female member. However, it has been recognized that with this arrangement, the buckle is susceptible to failure during heavy loading for the following reasons. The load in the latch arms which urges removal of the latch arms from the female member is ordinarily directed along the longitudinal axis or center line X of each latch arm. However, the line Y, which represents the location of the latch resistance or engagement force opposing the load, is offset from center line X because it is directed between the side walls of the female member and the shoulders on the outside side surfaces of the latch arms. Accordingly, it has been recognized that during loading on the buckle, a torque develops between the latch arms and the female member which tends to cause inward rotation of the latch arms in the direction of arrow Z (see FIG. 4), and consequently release of the buckle (see also U.S. Pat. No. 5,222,279 (col. 1, 1. 43-48).
U.S. Pat. No. 5,222,279 proposes a solution to this problem. In accordance with this patent, the shoulders on the latch arms are relocated from the outside side surfaces thereof to the top and bottom surface of each arm (see FIGS. 1 and 2). Thus, each arm has a pair of shoulders on opposite top and bottom sides of the arm (i.e., the top and bottom of the arm), and the shoulders are on opposite sides of the longitudinal axis or central line of each latch arm. The shoulders engage corresponding stop members in the female member of the buckle. Since the shoulders are no longer positioned on the outside side surfaces of the latch arms, and since the shoulders are aligned, in one direction, with the central or longitudinal axis of the latch arms, the latch resistance force which opposes the load on the buckle is aligned, in one direction, with the load force.
However, since the shoulders on the latch arms of the buckle described in U.S. Pat. No. 5,222,279 are located on opposite sides (i.e., the top and bottom) of the longitudinal axis of the latch arm, the latch resistance force opposing the load is merely aligned in one direction (i.e., in the "width" direction) with the load force. The latch resistance force is not aligned with the longitudinal or central axis of the latch arms in all planes and directions.
Published U.K. Patent Application GB 2 262 962 also proposes a solution to the problem of misalignment of the latch resistance or engagement force with the load force which occurs in the prior art buckles wherein the shoulders are defined in the outside side surfaces of the latch arms. The proposed solution is similar to the one described in U.S. Pat. No. 5,222,279 in that it involves the provision of engagement shoulders on the top and bottom surfaces of the latch arms. The engagement shoulders or surfaces on the latch arms are grooves which are adapted to mate with corresponding ridges in the female member of the buckle. The engagement or latch resistance force between the grooves on the latch arms and the ridges in the female member is aligned, in one direction, with the longitudinal or center axis of the latch arms. However, like the buckle described in U.S. Pat. No. 5,222,279, the latch resistance force is not aligned along the longitudinal axis of the latch arms in all directions, but rather it is located on opposite (i.e., top and bottom) surfaces of the latch arms.
It would therefore be desirable to provide a side-release buckle wherein the engagement force between the male and female members, which opposes the load force, is aligned in all directions with the longitudinal or central axis of the latch arms belonging to the male member, rather than being aligned merely in one direction, in order to further improve the locking strength of the buckle.